Head to Burning Blade Coven (the cave north of Valley of Trials). Fight your way inside and keep going until you reach a three-way intersection. First take the middle path. Go a few steps forward and you should see [Thazz'ril's Pick] glowing in the dark. Pick it up and go back to the intersection.

If you are less than 2400 XP into level 5 (or 2100 if you're a Priest) start killing boars and scorpids on your way, until you reach that quota. You want to ding level 6 after you turn in quests in Razor Hill.

Once you are inside the building, carefully fight your way up the stairs. Once you pass a porch, look to your left. There is a small slope going up into the room Lieutenant Benedict is in. Kill everyone in the room, except Benedict and his bodyguard. Once you're at full health and mana, brace yourself and attack. A healing potion could provide useful.